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 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
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 * without restriction, including without limitation the rights to copy, create
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 * Software and the Larger Work(s), and to sublicense the foregoing rights on
 * either these or other terms.
 *
 * This license is subject to the following condition:
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 * The above copyright notice and either this complete permission notice or at a
 * minimum a reference to the UPL must be included in all copies or substantial
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package com.oracle.truffle.regex.flavor.python;

import org.graalvm.shadowed.com.ibm.icu.lang.UCharacter;

import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.regex.RegexLanguage;
import com.oracle.truffle.regex.RegexSource;
import com.oracle.truffle.regex.charset.UnicodeProperties;
import com.oracle.truffle.regex.charset.UnicodePropertyDataVersion;
import com.oracle.truffle.regex.tregex.buffer.CompilationBuffer;
import com.oracle.truffle.regex.tregex.parser.CaseFoldData;
import com.oracle.truffle.regex.tregex.parser.RegexFlavor;
import com.oracle.truffle.regex.tregex.parser.RegexLexer;
import com.oracle.truffle.regex.tregex.parser.RegexParser;
import com.oracle.truffle.regex.tregex.parser.RegexValidator;
import com.oracle.truffle.regex.tregex.parser.ast.RegexAST;
import com.oracle.truffle.regex.tregex.string.Encoding;

/**
 * An implementation of the Python regex flavor. Supports both string regexes ('str' patterns) and
 * binary regexes ('bytes' patterns).
 *
 * @see PythonREMode
 */
public final class PythonFlavor extends RegexFlavor {

    public static final PythonFlavor INSTANCE = new PythonFlavor();
    public static final UnicodeProperties UNICODE = new UnicodeProperties(UnicodePropertyDataVersion.UNICODE_15_1_0, 0, UnicodeProperties.NameMatchingMode.exact);

    private PythonFlavor() {
        super(BACKREFERENCES_TO_UNMATCHED_GROUPS_FAIL | NESTED_CAPTURE_GROUPS_KEPT_ON_LOOP_REENTRY | FAILING_EMPTY_CHECKS_DONT_BACKTRACK | USES_LAST_GROUP_RESULT_FIELD |
                        LOOKBEHINDS_RUN_LEFT_TO_RIGHT | NEEDS_GROUP_START_POSITIONS | HAS_CONDITIONAL_BACKREFERENCES | LOOKBEHINDS_REQUIRE_FIXED_WIDTH_PATTERN);
    }

    @Override
    public String getName() {
        return "Python";
    }

    @Override
    public RegexValidator createValidator(RegexLanguage language, RegexSource source, CompilationBuffer compilationBuffer) {
        throw new UnsupportedOperationException();
    }

    @Override
    public RegexLexer createLexer(RegexSource source, CompilationBuffer compilationBuffer) {
        return new PythonRegexLexer(source, PythonREMode.fromEncoding(source.getEncoding()), compilationBuffer);
    }

    @Override
    public RegexParser createParser(RegexLanguage language, RegexSource source, CompilationBuffer compilationBuffer) {
        return new PythonRegexParser(language, source, compilationBuffer);
    }

    @Override
    public EqualsIgnoreCasePredicate getEqualsIgnoreCasePredicate(RegexAST ast) {
        if (ast.getOptions().getEncoding() == Encoding.UTF_32) {
            return (codePointA, codePointB, altMode) -> UCharacter.toLowerCase(codePointA) == UCharacter.toLowerCase(codePointB);
        } else {
            assert ast.getOptions().getEncoding() == Encoding.LATIN_1;
            return (a, b, altMode) -> CaseFoldData.CaseFoldUnfoldAlgorithm.Ascii.getEqualsPredicate().test(a, b);
        }
    }

    @Override
    public CaseFoldData.CaseFoldAlgorithm getCaseFoldAlgorithm(RegexAST ast) {
        throw CompilerDirectives.shouldNotReachHere();
    }
}
